keymap.c

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/*
 * Copyright (C) 2022 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );

#include <string.h>
#include <ctype.h>
#include <ipxe/keys.h>
#include <ipxe/keymap.h>

/** @file
 *
 * Keyboard mappings
 *
 */

/** ASCII character mask */
#define ASCII_MASK 0x7f

/** Control character mask */
#define CTRL_MASK 0x1f

/** Upper case character mask */
#define UPPER_MASK 0x5f

/** Case toggle bit */
#define CASE_TOGGLE ( ASCII_MASK & ~UPPER_MASK )

/** Default keyboard mapping */
static TABLE_START ( keymap_start, KEYMAP );

/** Current keyboard mapping */
static struct keymap *keymap_current = keymap_start;

/**
 * Remap a key
 *
 * @v character         Character read from console
 * @ret mapped          Mapped character
 */
unsigned int key_remap ( unsigned int character ) {
        struct keymap *keymap = keymap_current;
        unsigned int mapped = ( character & KEYMAP_MASK );
        struct keymap_key *key;

        /* Invert case before remapping if applicable */
        if ( ( character & KEYMAP_CAPSLOCK_UNDO ) && isalpha ( mapped ) )
                mapped ^= CASE_TOGGLE;

        /* Select remapping table */
        key = ( ( character & KEYMAP_ALTGR ) ? keymap->altgr : keymap->basic );

        /* Remap via table */
        for ( ; key->from ; key++ ) {
                if ( mapped == key->from ) {
                        mapped = key->to;
                        break;
                }
        }

        /* Handle Ctrl-<key> and CapsLock */
        if ( isalpha ( mapped ) ) {
                if ( character & KEYMAP_CTRL ) {
                        mapped &= CTRL_MASK;
                } else if ( character & KEYMAP_CAPSLOCK ) {
                        mapped ^= CASE_TOGGLE;
                }
        }

        /* Clear flags */
        mapped &= ASCII_MASK;

        DBGC2 ( &keymap_current, "KEYMAP mapped %04x => %02x\n",
                character, mapped );
        return mapped;
}

/**
 * Find keyboard map by name
 *
 * @v name              Keyboard map name
 * @ret keymap          Keyboard map, or NULL if not found
 */
struct keymap * keymap_find ( const char *name ) {
        struct keymap *keymap;

        /* Find matching keyboard map */
        for_each_table_entry ( keymap, KEYMAP ) {
                if ( strcmp ( keymap->name, name ) == 0 )
                        return keymap;
        }

        return NULL;
}

/**
 * Set keyboard map
 *
 * @v keymap            Keyboard map, or NULL to use default
 */
void keymap_set ( struct keymap *keymap ) {

        /* Use default keymap if none specified */
        if ( ! keymap )
                keymap = keymap_start;

        /* Set new keyboard map */
        if ( keymap != keymap_current )
                DBGC ( &keymap_current, "KEYMAP using \"%s\"\n", keymap->name );
        keymap_current = keymap;
}